IHS Anatomy and Physiology of Hearing 2 — Questions and Answers
Question 1: Which structure in the inner ear is responsible for converting mechanical vibrations into electrical signals?
- Tympanic membrane
- Organ of Corti (Correct answer)
- Eustachian tube
- Semicircular canals
Correct answer: Organ of Corti
The Organ of Corti, located in the cochlea, contains hair cells that transduce mechanical vibrations into neural electrical signals.
Question 2: The tonotopic organization of the cochlea means that:
- All frequencies are processed equally throughout
- High frequencies are processed at the apex and low at the base
- Low frequencies are processed at the apex and high at the base (Correct answer)
- The cochlea processes only speech frequencies
Correct answer: Low frequencies are processed at the apex and high at the base
The cochlear base responds to high frequencies while the apex responds to low frequencies, a spatial arrangement called tonotopy.
Question 3: What is the primary function of the Eustachian tube?
- Amplify sound vibrations entering the ear
- Equalize air pressure between the middle ear and nasopharynx (Correct answer)
- Drain endolymph from the cochlea
- Connect the cochlea to the auditory cortex
Correct answer: Equalize air pressure between the middle ear and nasopharynx
The Eustachian tube connects the middle ear to the nasopharynx, allowing pressure equalization on both sides of the tympanic membrane.
Question 4: Which type of hair cells are most numerous in the cochlea and primarily responsible for amplification?
- Inner hair cells
- Outer hair cells (Correct answer)
- Spiral ganglion cells
- Supporting cells
Correct answer: Outer hair cells
Outer hair cells (approximately 12,000) act as a cochlear amplifier by actively changing length, boosting sensitivity and frequency selectivity.
Question 5: The scala vestibuli and scala tympani are filled with:
- Endolymph
- Perilymph (Correct answer)
- Cerebrospinal fluid
- Aqueous humor
Correct answer: Perilymph
Perilymph, which resembles extracellular fluid in ionic composition, fills both the scala vestibuli and scala tympani.
Question 6: Damage to which nerve is responsible for sensorineural hearing loss in acoustic neuroma?
- Facial nerve (CN VII)
- Trigeminal nerve (CN V)
- Vestibulocochlear nerve (CN VIII) (Correct answer)
- Vagus nerve (CN X)
Correct answer: Vestibulocochlear nerve (CN VIII)
Acoustic neuromas (vestibular schwannomas) grow on CN VIII, compressing it and causing progressive sensorineural hearing loss.
Question 7: The helicotrema is located:
- At the oval window where the stapes footplate sits
- At the apex of the cochlea connecting the two scalae (Correct answer)
- At the round window membrane
- Between the utricle and saccule
Correct answer: At the apex of the cochlea connecting the two scalae
The helicotrema is the small opening at the cochlear apex where the scala vestibuli and scala tympani communicate.
IHS Anatomy and Physiology of Hearing 2
Which structure in the inner ear is responsible for converting mechanical vibrations into electrical signals?